ISSN:
1095-8649
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Cannibalism in walleye pollock off the eastern coast of the Hokkaido Island, Japan was important only during spring (April to June), and its importance increased from 0% in dry mass for 〈200 mm LS fish to 48·9% for 〉400 mm LS fish. Most of the prey was represented by age 1 year fish, showing a unimodal body size distribution with a mode at 121–130 mm. Although cannibal body size was larger in deeper (〉150 m) water, there was no difference in prey size by depth, suggesting impingement of the predators inhabiting deeper water into the shallow areas to cannibalize 1 year fish. The minimum ratio cannibal: prey size was 1·74. There was a positive but non-significant correlation between the contribution of cannibalism to a potential predator's (〉300 mm) diet and an estimate of the previous year's recruitment. This was due to an extremely high contribution of cannibalism during 1992, when a distinctly larger size of predators seemed to bias the contribution. When the 1992 data were removed from the analysis, a significant correlation was obtained (r2=0·77, P〈0·01), showing that Pollock cannibalism is rather density dependent. Based on the results, it is hypothesized that the‘overflow’ of 1 year fish from the shelf waters due to their high abundance and the weak stratification in the spring water column results in increased co-occurrence with adult fish and consequent cannibalism.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1095-8649.2001.tb02368.x
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